The U.N. wants $7 billion. You won't believe how much it may yet need

Almost as soon as the United Nations announced that it had developed a figure for the cost of the fight against AIDS in Africa earlier this spring, Washington started to fret. The number, the Administration said, was just too big. Other donor nations were also concerned that the figure was unrealistic. The sum would be hard to raise. Moreover, a U.N. official explained, Washington was concerned that the U.S. contribution would "look like a drop in the bucket."

But this wasn't a number that could be fiddled. Much as donor nations might have liked to round the overall number down, the...